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Author Topic: new greenhouse planning  (Read 5211 times)

Mark in Texas

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Re: new greenhouse planning
« Reply #25 on: December 26, 2015, 09:42:40 PM »
Sounds good.  I let my lows go down to 34F.  I'm cheap. :)

Millet

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Re: new greenhouse planning
« Reply #26 on: December 26, 2015, 10:16:14 PM »
Mark nothing wrong with letting the greenhouse temperature get as low as possible.  It saves on the propane bill. Your giving up winter growth for lower propane bills. Besides  central Texas has many more warm daytime temperatures, and higher nighttime temperatures then does Colorado - Millet
« Last Edit: December 26, 2015, 10:19:13 PM by Millet »

brian

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Re: new greenhouse planning
« Reply #27 on: December 26, 2015, 11:28:34 PM »
That looks like a really nice greenhouse, Mark.  Do you have active cooling?  How does it handle the Texas summers?

When doing heating calculations I'm using 55F as the maintained temperature, however with my current setup I have my heaters set to 55F but they are undersized and allow the temperature to drop to ~35F when its below 0F outside.  I'd like to start growing actual tropicals with the new greenhouse so I'm trying to do all I can to have a reasonably high minimum temperature. 

From playing with various heating cost calculations it seems the largest controllable factor by far in heating costs is the target minimum temperature.  Dropping this by a small amount has a huge savings compared to using thicker glazing.  Decreasing overall surface area has a large effect too.

Mark in Texas

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Re: new greenhouse planning
« Reply #28 on: December 27, 2015, 12:28:06 PM »
Have 2 swamp coolers now.  Plan on installing flash nozzles run by a very high pressure (1,000 PSI) pump.  I hit over 100F often in the summer.

Don't get too anal about climate control.  It will all have to be tweeked come reality.  Mass plays a huge part too. 15 trees with large canopies store a lot of heat compared to a dozen tomato plants.   

You're right Millet.  This greenhouse stuff is a toy anyway.  Another one of my man caves.  ;)
« Last Edit: December 27, 2015, 12:30:42 PM by Mark in Texas »

Millet

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Re: new greenhouse planning
« Reply #29 on: December 28, 2015, 11:54:41 AM »
I remembered reading (about 10 years ago) about a double poly air inflated greenhouse insulation system where polystyrene pellets were blown into the two inch space between the double poly layers at night, thus filling up the space providing almost complete insulation, and then blown back out the next morning leaving the  root clear to receive the sun's light during the day.  The claim was a 90% heat savings.  Therefore, I tried to find the system on the internet.  Below is a link to how this was achieved. - Millet

https://etd.ohiolink.edu/rws_etd/document/get/osu1295548226/inline

brian

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Re: new greenhouse planning
« Reply #30 on: December 28, 2015, 01:06:49 PM »
This is an excellent idea, I am curious about their design.  Reading the document now...

I had wondered about adding additional layers of inflated PET to acheive 3x, 4x, etc.  but I imagine it is similar to having multiple layers of PC where you start to lose light transmission considerably. 

« Last Edit: December 28, 2015, 01:44:00 PM by brian »

brian

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Re: new greenhouse planning
« Reply #31 on: December 28, 2015, 01:49:10 PM »
That's a really clever idea.  It sounds like their implementation had some problems.  The only potential improvements I can think of would be to use something like ping pong balls instead of styrofoam pellets for better flow, and to use a rollup/retracting "dryer exhaust" type tube instead of the zipper tubes they tried.  It seems it also takes a lot of tuning to get the flow just right and avoid plugs.  Finally, the biggest problem I can see for me trying something like this in a residential area is the possibility of millions of styrofoam bits spilling all over the neighborhood if something bursts.  That would make me very unpopular.

I'm trying to think of other similar designs where insulating material can be moved into place along the roof with pneumatics instead of pulleys & tracks.  The ability to store the insulating material outside the greenhouse is some kind of reservoir (instead of folded up, limiting its thickness) is a huge win.

brian

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Re: new greenhouse planning
« Reply #32 on: December 28, 2015, 01:53:58 PM »
Seeing as I have a bunch of leftover fiberglass rolls from my current greenhouse construction and various tarps, I am thinking of doing a mockup of the proposed thermal blanket design to see how well it slides up a polycarbonate face, especially when wet. 

Mark in Texas

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Re: new greenhouse planning
« Reply #33 on: December 28, 2015, 02:14:35 PM »
There's always unintended consequences.  I wonder if static electricity would stick those foam balls to plastic like glue.

Daintree

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Re: new greenhouse planning
« Reply #34 on: January 04, 2016, 08:31:57 AM »
Thanks for the information Daintree.  I will hold off on an evaporative cooling system until it proves to be necessary.  I am hoping shade cloth + ventilation will be enough.

However, I think you are mistaken about the CO2 emissions of burning natural gas.  This absolutely produces significant amounts of CO2.  You may be thinking about Hydrogen which only produces water vapor.  I am also thinking about putting birds in my greenhouse.  How does it work out for you?  I'd worry about them destroying smaller plants.   And if you are running an unvented heater with birds living inside and have no issues that is encouraging in terms of emissions safety.




Well, that just shows you how much I know about chemistry!

Of course, my greenhouse is not a tight construction so I don't have to have a vented heater.  I do know that the blue flame heater DOES make a lot of water vapor, which is great with our low humidity. Mine is 20,000 BTUs.

As for the birds, they do great out there (some have lived out there for 7 years).  I have nets under their perches (poop-catchers!) for MY comfort, and my seedlings live on racks that I have covered with cheap, green plastic fencing.  The poles that my vanilla orchids and Nigerian walnuts are on are also fenced in.  The green plastic fencing is easy to work with and blends in pretty well with the general "decor" of the place.
The birds do read Latin, and can count, however!  They only go for plants that have "edulis" or "deliciosa" on the tag, or that were particularly expensive to purchase…
Some bird species are more destructive than others, so shop carefully. Giving them something they are allowed to eat helps a lot.  Mine LOVE chia pets! 

You can see the furnace on the back wall in the picture.  Notice what looks like bbq racks on the front of the heater - that keeps the birds from exploring during the non-heating season.  They are cavity nesters, and are in to every nook and cranny in the place!  I am trying to build a fake tree for nesting, but I am on about failure #6 right now. They have to put up with unrealistic-looking bird houses right now.

It's an ecosystem that is tremendous fun, but always teetering on the brink of chaos.

I don't know why the shade cloth directly on the greenhouse held in heat, but it really made a HUGE difference to put it on a frame.  A friend here in town with a greenhouse had the same problem.  My guess is the size of our backyard greenhouses, compared to a commercial type of setup.  My ceiling height is only a little over 10 ft. Also, I don't have roof-top vents.  I have a 3 ft window on one end, and an exhaust fan at the top of the opposite end wall. 

Here is my granddaughter with one of my Bourke's grasskeets (anything she loves, she kisses.  My plants are also well-kissed!)

Cheers!
Carolyn


brian

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Re: new greenhouse planning
« Reply #35 on: January 04, 2016, 05:10:55 PM »
This is great to hear, Daintree.  Glad things are working out so well for you.  I'd definitely like to keep a few birds in mine.

brian

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Re: new greenhouse planning
« Reply #36 on: August 25, 2016, 09:57:34 PM »
So I am moving forward with this project.  I decided to go with a significantly smaller greenhouse when my wife pointed out that the 30x48' design I was looking out had a bigger footprint than our house!  So now I am considering this one:


Because of the local township rules I need a 3ft deep foundation if its over 600sf, and only a 1ft foundation if its under 600sf.  This model comes in 18ft width and 4ft lengths so I'm going with either 32' (576sf) or 36' (648sf) depending on how deep I want to go.  The current question I have is how deep I should be insulating the ground for in-ground trees.  A quick google search says "Like most trees, the majority of the orange tree's roots are concentrated in the top 2 feet of the soil".   The International Residential Building Code specifies vertical insulation only 1ft deep to avoid freezing, but I'm shooting for a much warmer root zone.  At larger depths, a combination of vertical and horizontal insulation is called for.

So, the easier method would be to something like this with 18x32' greenhouse, 1ft deep foundation, 1ft of vertical and 1ft of horizontal insulation (minus the slab floor):


However, I'm going to have to rent a trench digging tool anyway, and I think they go down to 3ft.  So, it might not be much harder to do a 3ft than 1ft.  If this is the case I can just do 3ft deep vertical insulation along the foundation wall and the tree roots will be stuck inside the foundation anyway so I shouldn't need any skirt insulation.  This would let me build a slightly bigger 18x36'.  Increased concrete costs, minor increase in greenhouse cost

So... I'm thinking I may order the 36' length and see if I hit a bunch of rocks when digging.  If it looks sketchy I can skip the last 4' section and do the 1ft foundation.

Mark in Texas

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Re: new greenhouse planning
« Reply #37 on: August 26, 2016, 09:52:19 AM »
What brand?  Looks like my Dad's from Texas Greenhouses.

I would look hard at a Nexus. I have the 30X36' Zephr and love it. It's fully automated with roof and wall vents, iLink controller, two 1 HP Locke motors.



Millet, recently replaced the Palram SolarSoft85 with clear Lexan on the north roof.



« Last Edit: August 26, 2016, 10:01:50 AM by Mark in Texas »

brian

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Re: new greenhouse planning
« Reply #38 on: August 26, 2016, 10:30:58 AM »
This is a Conley's Hobby House w 6mm dual-polycarbonate panels all around.  I'd prefer 8mm but they said it can't flex enough at the eaves. 

I did look at the Zephyr you have but it is a bit taller than I'm looking for.  Also, I'm wasn't sure how well natural ventillation would work out with inconsistent winds.  Glad to hear it does work for you!
« Last Edit: August 26, 2016, 11:20:46 AM by brian »

Mark in Texas

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Re: new greenhouse planning
« Reply #39 on: August 26, 2016, 10:50:02 AM »
Conley's an excellent house and my first choice with high columns.  Never could get a 3rd party rep here in Texas to get it done so I switched to Nexus.  I wanted a tall roof cause I'm growing big trees like avocados, citrus and mangos.  My Reed avocado here is over 10' tall and this photo doesn't do it justice regarding the wide angle shot.






BTW, I made a warranty claim to Palram for the roof SolarSoft85, griping about the loss of light transmission after 3 years.  Their specs said it came in at 76%.   In spite of folks in this biz warning me my claim "will never happen" they replaced the roof covering free which included a big expense of crating and shipping a 26' long crate.  Could not believe it! Now that's service!  It was actually Green Tek, a Palram rep that replaced it.


« Last Edit: August 26, 2016, 10:52:16 AM by Mark in Texas »

brian

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Re: new greenhouse planning
« Reply #40 on: August 26, 2016, 11:19:45 AM »
The one I'm looking at is 5.5ft at the edges (eaves) and 11.5ft at peak.   So, my plan is to put my most vigorous trees in the center and smaller ones along the edge.  Given my experience with temperate in-ground fruit trees, anything taller requires a ladder to pick and I'm just too lazy to use one so I prune me trees above this height.

I am planning to order through IGC (aka greenhousemegastore.com) as they seem to have a great reputation and their sales people have been very helpful.  I'm going to build it myself with some friends.   

Your trees look awesome.  I'm excited to get this set up.   
« Last Edit: September 22, 2016, 07:57:20 AM by brian »

Mark in Texas

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Re: new greenhouse planning
« Reply #41 on: August 26, 2016, 02:49:03 PM »
Another reason why I used 10' columns is to get the heat off the trees.  You probably don't have to worry about summer heat but for very short periods. 

Good luck Brian!   Not to worry, that first orange will only costs $30,000!   ;D  I have lots of different tropical fruits including pineapples. They are pure sugar juice. 



Millet

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Re: new greenhouse planning
« Reply #42 on: August 26, 2016, 02:59:23 PM »
Brian, won't insulation on the outside of the walls get soaked?  Insulation that becomes soaked loses all insulation value.   Be absolutely sure you build all the greenhouse you need.  After the greenhouse is up it is to late.  I now wish  my 32' X 72' was 32' X 100'.   They fill up fast.   
Millet

SusanB

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Re: new greenhouse planning
« Reply #43 on: September 21, 2016, 03:33:53 PM »
Hi Brian,
I'm late to the discussion but I have a 21 x 36 Natural Greenhouse that you were first looking at.  We like it quite a bit except for some minor drawbacks. 
1).  It's big.  I made a mistake calculating, I looked at the plants in our house (8ft ceiling) and then decided to go with the 8 foot sidewalls.  Our land wasn't as level as I thought, so they had to build a wall for the GH to sit on.  So, it is TALL.
2) We put it up ourselves except for the initial wall and most of the roof polycarbonate.  We finally rented a cherry picker and some handymen and it was very easy then.
3)  It does cost a lot to heat.  I don't remember what we kept it at the first winter, maybe as high as 70, but it cost $2000 for the propane.  We put in a wood stove that does most of the heating now.  We get 1 tank load a year, about $500 depending on prices.   And no, the stove does not affect the plants at all, although they did get a bit sooty at times.
4) The inflatable sidewalls work great until they don't.  The back up batteries do fine for about 2 hours, but you should have a generator just in case of longer power outages. 
5) Invest in a concrete floor if you can.  We live on a rocky clearing where there is no dirt or grass, and a lot of dust.  The dirt floor of the GH also makes a lot of dust.  This gets on the inside vents, walls, and parts.  We've never had problems with the 2 fans, but we have had blowers go out.  My husband was thrilled to replace them at 2 am with snow coming in the vents.  And yes, the plants were fine.
6) If you have regular breezes, the natural ventilation works great.  We get very little wind here and in the summer the greenhouse is super-hot, even with all the vents and doors open.  Having grass around the GH would probably help a bit with that, too.   

I've tried to load a photo but not sure if it will go through. 

Millet

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Re: new greenhouse planning
« Reply #44 on: September 21, 2016, 09:19:46 PM »
Susan, have ever given thought about investing in a shade cloth to cool the greenhouse during the summer..   There is a great one called Aluminet which is a silver sideded net that reflects much of the sun's radiation away.  I use a 30% shade net. Thanks for joining the forum.  Take care. - Millet
« Last Edit: September 21, 2016, 09:21:25 PM by Millet »

SusanB

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Re: new greenhouse planning
« Reply #45 on: September 22, 2016, 12:04:04 AM »
Hi Millet, nice to be back!  It doesn't matter.  with our rock it's like living in the middle of a concrete parking lot, the ground doesn't absorb the heat, just reflects it up.  I have a 20 ft shadecloth (black) on the outside which does help a bit in the winter.  And I do have a couple of trees that live in there year around, 2 Ceiba speciosa and a Bursera simbaruba (probably spelled wrong) that do OK with the temps getting 120 or more.  Which I guess is only 30 degrees warmer than the 90 degrees we had for so much of the summer so it's to be expected.  Citrus table to the right.


brian

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Re: new greenhouse planning
« Reply #46 on: September 22, 2016, 07:56:39 AM »
Brian, won't insulation on the outside of the walls get soaked?  Insulation that becomes soaked loses all insulation value.   Be absolutely sure you build all the greenhouse you need.  After the greenhouse is up it is to late.  I now wish  my 32' X 72' was 32' X 100'.   They fill up fast.   
Millet

Millet, the rigid foam insulation I'll be using on the foundation exterior is impermeable so this should not be a problem.  This type of insulation foundation design is specifically allowed by the International Building Code and recommended for energy efficiency and material savings.

As for size, I would like to have gone larger but the building regulations would have made it prohibitively expensive for me.  And actually, can't you simply expand yours?  They're generally sold in 4-6ft increments.  I imagine if you could disconnect the exterior wall during mild weather and add a few sections?

brian

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Re: new greenhouse planning
« Reply #47 on: September 22, 2016, 08:08:23 AM »
Hi Brian,
I'm late to the discussion but I have a 21 x 36 Natural Greenhouse that you were first looking at.  We like it quite a bit except for some minor drawbacks. 
1).  It's big.  I made a mistake calculating, I looked at the plants in our house (8ft ceiling) and then decided to go with the 8 foot sidewalls.  Our land wasn't as level as I thought, so they had to build a wall for the GH to sit on.  So, it is TALL.
2) We put it up ourselves except for the initial wall and most of the roof polycarbonate.  We finally rented a cherry picker and some handymen and it was very easy then.
3)  It does cost a lot to heat.  I don't remember what we kept it at the first winter, maybe as high as 70, but it cost $2000 for the propane.  We put in a wood stove that does most of the heating now.  We get 1 tank load a year, about $500 depending on prices.   And no, the stove does not affect the plants at all, although they did get a bit sooty at times.
4) The inflatable sidewalls work great until they don't.  The back up batteries do fine for about 2 hours, but you should have a generator just in case of longer power outages. 
5) Invest in a concrete floor if you can.  We live on a rocky clearing where there is no dirt or grass, and a lot of dust.  The dirt floor of the GH also makes a lot of dust.  This gets on the inside vents, walls, and parts.  We've never had problems with the 2 fans, but we have had blowers go out.  My husband was thrilled to replace them at 2 am with snow coming in the vents.  And yes, the plants were fine.
6) If you have regular breezes, the natural ventilation works great.  We get very little wind here and in the summer the greenhouse is super-hot, even with all the vents and doors open.  Having grass around the GH would probably help a bit with that, too.   

I've tried to load a photo but not sure if it will go through.

Great to hear others experience with this, thank you.

My ground is a bit sloped also, so one side of the greenhouse will be about 3ft taller than the other.  This puts it to about 14ft which isn't too bad for me.   I had done a lot of heating cost calculations before I started.  When house hunting with my wife I specifically looked for natural gas availability because natural gas is something like half the cost of propane, or better!   Previously in my old improvised greenhouse I was heating with electric space heaters which even with a off-peak rate was pricey.

You brought up a very very good point I hadn't thought about... back up power.   I bought a back up heater but I believe it still needs electricity.  I will have to look into this.  I think a back up battery might be sufficient as the electrical draw for a gas heater is likely very small.

And as for dirt/dust... I agree with you it could be a problem so I was planning on planting grass or any kind of groundcover between trees. 

For ventilation... I have been meaning to investigate weather the added CO2 from allowing gas exhaust into the greenhouse would be beneficial or a negative because of the small amount of pollution that comes along with it.  The heaters I purchased are vented outside but I could always introduce a leak if I wanted to allow some exhaust in.  I am thinking I shuold get carbon monoxide detectors regardless.

brian

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Re: new greenhouse planning
« Reply #48 on: September 22, 2016, 08:12:32 AM »
Today the foundation excavation will be complete and I will start building concrete forms for the foundation.  The actual greenhouse kit won't be delivered for a few weeks as Conleys manufactures them to order so they are still cutting it.

Mark in Texas

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Re: new greenhouse planning
« Reply #49 on: September 22, 2016, 08:26:10 AM »
Happy to hear it's coming along. Good luck!

 

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